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| author | sanine <sanine.not@pm.me> | 2023-03-11 15:58:20 -0600 |
|---|---|---|
| committer | sanine <sanine.not@pm.me> | 2023-03-11 15:58:20 -0600 |
| commit | ebc50b387ab209c9f9a0d92e340ac293d5697274 (patch) | |
| tree | ea8c8b3677a18c994d2b9d33dbef3461dcf18113 /libs/luajit-cmake/luajit/doc/ext_profiler.html | |
| parent | c2329b4c8258baa9429c77566c9def97d00e96d7 (diff) | |
build & link with luajit instead of lua5.1
Diffstat (limited to 'libs/luajit-cmake/luajit/doc/ext_profiler.html')
| -rw-r--r-- | libs/luajit-cmake/luajit/doc/ext_profiler.html | 359 |
1 files changed, 359 insertions, 0 deletions
diff --git a/libs/luajit-cmake/luajit/doc/ext_profiler.html b/libs/luajit-cmake/luajit/doc/ext_profiler.html new file mode 100644 index 0000000..d6e26ef --- /dev/null +++ b/libs/luajit-cmake/luajit/doc/ext_profiler.html @@ -0,0 +1,359 @@ +<!DOCTYPE html> +<html> +<head> +<title>Profiler</title> +<meta charset="utf-8"> +<meta name="Copyright" content="Copyright (C) 2005-2022"> +<meta name="Language" content="en"> +<link rel="stylesheet" type="text/css" href="bluequad.css" media="screen"> +<link rel="stylesheet" type="text/css" href="bluequad-print.css" media="print"> +</head> +<body> +<div id="site"> +<a href="https://luajit.org"><span>Lua<span id="logo">JIT</span></span></a> +</div> +<div id="head"> +<h1>Profiler</h1> +</div> +<div id="nav"> +<ul><li> +<a href="luajit.html">LuaJIT</a> +<ul><li> +<a href="https://luajit.org/download.html">Download <span class="ext">»</span></a> +</li><li> +<a href="install.html">Installation</a> +</li><li> +<a href="running.html">Running</a> +</li></ul> +</li><li> +<a href="extensions.html">Extensions</a> +<ul><li> +<a href="ext_ffi.html">FFI Library</a> +<ul><li> +<a href="ext_ffi_tutorial.html">FFI Tutorial</a> +</li><li> +<a href="ext_ffi_api.html">ffi.* API</a> +</li><li> +<a href="ext_ffi_semantics.html">FFI Semantics</a> +</li></ul> +</li><li> +<a href="ext_buffer.html">String Buffers</a> +</li><li> +<a href="ext_jit.html">jit.* Library</a> +</li><li> +<a href="ext_c_api.html">Lua/C API</a> +</li><li> +<a class="current" href="ext_profiler.html">Profiler</a> +</li></ul> +</li><li> +<a href="status.html">Status</a> +</li><li> +<a href="faq.html">FAQ</a> +</li><li> +<a href="https://luajit.org/list.html">Mailing List <span class="ext">»</span></a> +</li></ul> +</div> +<div id="main"> +<p> +LuaJIT has an integrated statistical profiler with very low overhead. It +allows sampling the currently executing stack and other parameters in +regular intervals. +</p> +<p> +The integrated profiler can be accessed from three levels: +</p> +<ul> +<li>The <a href="#hl_profiler">bundled high-level profiler</a>, invoked by the +<a href="#j_p"><tt>-jp</tt></a> command line option.</li> +<li>A <a href="#ll_lua_api">low-level Lua API</a> to control the profiler.</li> +<li>A <a href="#ll_c_api">low-level C API</a> to control the profiler.</li> +</ul> + +<h2 id="hl_profiler">High-Level Profiler</h2> +<p> +The bundled high-level profiler offers basic profiling functionality. It +generates simple textual summaries or source code annotations. It can be +accessed with the <a href="#j_p"><tt>-jp</tt></a> command line option +or from Lua code by loading the underlying <tt>jit.p</tt> module. +</p> +<p> +To cut to the chase — run this to get a CPU usage profile by +function name: +</p> +<pre class="code"> +luajit -jp myapp.lua +</pre> +<p> +It's <em>not</em> a stated goal of the bundled profiler to add every +possible option or to cater for special profiling needs. The low-level +profiler APIs are documented below. They may be used by third-party +authors to implement advanced functionality, e.g. IDE integration or +graphical profilers. +</p> +<p> +Note: Sampling works for both interpreted and JIT-compiled code. The +results for JIT-compiled code may sometimes be surprising. LuaJIT +heavily optimizes and inlines Lua code — there's no simple +one-to-one correspondence between source code lines and the sampled +machine code. +</p> + +<h3 id="j_p"><tt>-jp=[options[,output]]</tt></h3> +<p> +The <tt>-jp</tt> command line option starts the high-level profiler. +When the application run by the command line terminates, the profiler +stops and writes the results to <tt>stdout</tt> or to the specified +<tt>output</tt> file. +</p> +<p> +The <tt>options</tt> argument specifies how the profiling is to be +performed: +</p> +<ul> +<li><tt>f</tt> — Stack dump: function name, otherwise module:line. +This is the default mode.</li> +<li><tt>F</tt> — Stack dump: ditto, but dump module:name.</li> +<li><tt>l</tt> — Stack dump: module:line.</li> +<li><tt><number></tt> — stack dump depth (callee ← +caller). Default: 1.</li> +<li><tt>-<number></tt> — Inverse stack dump depth (caller +→ callee).</li> +<li><tt>s</tt> — Split stack dump after first stack level. Implies +depth ≥ 2 or depth ≤ -2.</li> +<li><tt>p</tt> — Show full path for module names.</li> +<li><tt>v</tt> — Show VM states.</li> +<li><tt>z</tt> — Show <a href="#jit_zone">zones</a>.</li> +<li><tt>r</tt> — Show raw sample counts. Default: show percentages.</li> +<li><tt>a</tt> — Annotate excerpts from source code files.</li> +<li><tt>A</tt> — Annotate complete source code files.</li> +<li><tt>G</tt> — Produce raw output suitable for graphical tools.</li> +<li><tt>m<number></tt> — Minimum sample percentage to be shown. +Default: 3%.</li> +<li><tt>i<number></tt> — Sampling interval in milliseconds. +Default: 10ms.<br> +Note: The actual sampling precision is OS-dependent.</li> +</ul> +<p> +The default output for <tt>-jp</tt> is a list of the most CPU consuming +spots in the application. Increasing the stack dump depth with (say) +<tt>-jp=2</tt> may help to point out the main callers or callees of +hotspots. But sample aggregation is still flat per unique stack dump. +</p> +<p> +To get a two-level view (split view) of callers/callees, use +<tt>-jp=s</tt> or <tt>-jp=-s</tt>. The percentages shown for the second +level are relative to the first level. +</p> +<p> +To see how much time is spent in each line relative to a function, use +<tt>-jp=fl</tt>. +</p> +<p> +To see how much time is spent in different VM states or +<a href="#jit_zone">zones</a>, use <tt>-jp=v</tt> or <tt>-jp=z</tt>. +</p> +<p> +Combinations of <tt>v/z</tt> with <tt>f/F/l</tt> produce two-level +views, e.g. <tt>-jp=vf</tt> or <tt>-jp=fv</tt>. This shows the time +spent in a VM state or zone vs. hotspots. This can be used to answer +questions like "Which time-consuming functions are only interpreted?" or +"What's the garbage collector overhead for a specific function?". +</p> +<p> +Multiple options can be combined — but not all combinations make +sense, see above. E.g. <tt>-jp=3si4m1</tt> samples three stack levels +deep in 4ms intervals and shows a split view of the CPU consuming +functions and their callers with a 1% threshold. +</p> +<p> +Source code annotations produced by <tt>-jp=a</tt> or <tt>-jp=A</tt> are +always flat and at the line level. Obviously, the source code files need +to be readable by the profiler script. +</p> +<p> +The high-level profiler can also be started and stopped from Lua code with: +</p> +<pre class="code"> +require("jit.p").start(options, output) +... +require("jit.p").stop() +</pre> + +<h3 id="jit_zone"><tt>jit.zone</tt> — Zones</h3> +<p> +Zones can be used to provide information about different parts of an +application to the high-level profiler. E.g. a game could make use of an +<tt>"AI"</tt> zone, a <tt>"PHYS"</tt> zone, etc. Zones are hierarchical, +organized as a stack. +</p> +<p> +The <tt>jit.zone</tt> module needs to be loaded explicitly: +</p> +<pre class="code"> +local zone = require("jit.zone") +</pre> +<ul> +<li><tt>zone("name")</tt> pushes a named zone to the zone stack.</li> +<li><tt>zone()</tt> pops the current zone from the zone stack and +returns its name.</li> +<li><tt>zone:get()</tt> returns the current zone name or <tt>nil</tt>.</li> +<li><tt>zone:flush()</tt> flushes the zone stack.</li> +</ul> +<p> +To show the time spent in each zone use <tt>-jp=z</tt>. To show the time +spent relative to hotspots use e.g. <tt>-jp=zf</tt> or <tt>-jp=fz</tt>. +</p> + +<h2 id="ll_lua_api">Low-level Lua API</h2> +<p> +The <tt>jit.profile</tt> module gives access to the low-level API of the +profiler from Lua code. This module needs to be loaded explicitly: +<pre class="code"> +local profile = require("jit.profile") +</pre> +<p> +This module can be used to implement your own higher-level profiler. +A typical profiling run starts the profiler, captures stack dumps in +the profiler callback, adds them to a hash table to aggregate the number +of samples, stops the profiler and then analyzes all captured +stack dumps. Other parameters can be sampled in the profiler callback, +too. But it's important not to spend too much time in the callback, +since this may skew the statistics. +</p> + +<h3 id="profile_start"><tt>profile.start(mode, cb)</tt> +— Start profiler</h3> +<p> +This function starts the profiler. The <tt>mode</tt> argument is a +string holding options: +</p> +<ul> +<li><tt>f</tt> — Profile with precision down to the function level.</li> +<li><tt>l</tt> — Profile with precision down to the line level.</li> +<li><tt>i<number></tt> — Sampling interval in milliseconds (default +10ms).</br> +Note: The actual sampling precision is OS-dependent. +</li> +</ul> +<p> +The <tt>cb</tt> argument is a callback function which is called with +three arguments: <tt>(thread, samples, vmstate)</tt>. The callback is +called on a separate coroutine, the <tt>thread</tt> argument is the +state that holds the stack to sample for profiling. Note: do +<em>not</em> modify the stack of that state or call functions on it. +</p> +<p> +<tt>samples</tt> gives the number of accumulated samples since the last +callback (usually 1). +</p> +<p> +<tt>vmstate</tt> holds the VM state at the time the profiling timer +triggered. This may or may not correspond to the state of the VM when +the profiling callback is called. The state is either <tt>'N'</tt> +native (compiled) code, <tt>'I'</tt> interpreted code, <tt>'C'</tt> +C code, <tt>'G'</tt> the garbage collector, or <tt>'J'</tt> the JIT +compiler. +</p> + +<h3 id="profile_stop"><tt>profile.stop()</tt> +— Stop profiler</h3> +<p> +This function stops the profiler. +</p> + +<h3 id="profile_dump"><tt>dump = profile.dumpstack([thread,] fmt, depth)</tt> +— Dump stack </h3> +<p> +This function allows taking stack dumps in an efficient manner. It +returns a string with a stack dump for the <tt>thread</tt> (coroutine), +formatted according to the <tt>fmt</tt> argument: +</p> +<ul> +<li><tt>p</tt> — Preserve the full path for module names. Otherwise, +only the file name is used.</li> +<li><tt>f</tt> — Dump the function name if it can be derived. Otherwise, +use module:line.</li> +<li><tt>F</tt> — Ditto, but dump module:name.</li> +<li><tt>l</tt> — Dump module:line.</li> +<li><tt>Z</tt> — Zap the following characters for the last dumped +frame.</li> +<li>All other characters are added verbatim to the output string.</li> +</ul> +<p> +The <tt>depth</tt> argument gives the number of frames to dump, starting +at the topmost frame of the thread. A negative number dumps the frames in +inverse order. +</p> +<p> +The first example prints a list of the current module names and line +numbers of up to 10 frames in separate lines. The second example prints +semicolon-separated function names for all frames (up to 100) in inverse +order: +</p> +<pre class="code"> +print(profile.dumpstack(thread, "l\n", 10)) +print(profile.dumpstack(thread, "lZ;", -100)) +</pre> + +<h2 id="ll_c_api">Low-level C API</h2> +<p> +The profiler can be controlled directly from C code, e.g. for +use by IDEs. The declarations are in <tt>"luajit.h"</tt> (see +<a href="ext_c_api.html">Lua/C API</a> extensions). +</p> + +<h3 id="luaJIT_profile_start"><tt>luaJIT_profile_start(L, mode, cb, data)</tt> +— Start profiler</h3> +<p> +This function starts the profiler. <a href="#profile_start">See +above</a> for a description of the <tt>mode</tt> argument. +</p> +<p> +The <tt>cb</tt> argument is a callback function with the following +declaration: +</p> +<pre class="code"> +typedef void (*luaJIT_profile_callback)(void *data, lua_State *L, + int samples, int vmstate); +</pre> +<p> +<tt>data</tt> is available for use by the callback. <tt>L</tt> is the +state that holds the stack to sample for profiling. Note: do +<em>not</em> modify this stack or call functions on this stack — +use a separate coroutine for this purpose. <a href="#profile_start">See +above</a> for a description of <tt>samples</tt> and <tt>vmstate</tt>. +</p> + +<h3 id="luaJIT_profile_stop"><tt>luaJIT_profile_stop(L)</tt> +— Stop profiler</h3> +<p> +This function stops the profiler. +</p> + +<h3 id="luaJIT_profile_dumpstack"><tt>p = luaJIT_profile_dumpstack(L, fmt, depth, len)</tt> +— Dump stack </h3> +<p> +This function allows taking stack dumps in an efficient manner. +<a href="#profile_dump">See above</a> for a description of <tt>fmt</tt> +and <tt>depth</tt>. +</p> +<p> +This function returns a <tt>const char *</tt> pointing to a +private string buffer of the profiler. The <tt>int *len</tt> +argument returns the length of the output string. The buffer is +overwritten on the next call and deallocated when the profiler stops. +You either need to consume the content immediately or copy it for later +use. +</p> +<br class="flush"> +</div> +<div id="foot"> +<hr class="hide"> +Copyright © 2005-2022 +<span class="noprint"> +· +<a href="contact.html">Contact</a> +</span> +</div> +</body> +</html> |